Exposure of dairy cows to high environmental temperatures and their lactation status impairs establishment of the ovarian reserve in their offspring

The objectives of this study were to establish if exposure of pregnant dairy cows to high environmental temperatures and humidity during the first trimester of pregnancy impairs the establishment of the ovarian reserve (total number of healthy follicles and oocytes in ovaries) and fertility in their offspring. Serum anti-Müllerian hormone (AMH) concentrations and number of follicles ≥3 mm (antral follicle count; AFC) were assessed on a random day of the estrous cycle in 310 sixteen-month-old dairy heifers. Based on season of their conception and early fetal life, heifers were separated into 2 groups: summer (mean monthly temperature-humidity index = 69.33 ± 2.6) and winter (temperature-humidity index = 54.91 ± 1.08). The AMH and AFC were lower in summer (419.27 ± 22.81 pg/mL and 9.32 ± 0.42 follicles, respectively) compared with winter heifers (634.91 ± 47.60 pg/mL and 11.84 ± 0.46 follicles, respectively) and were not influenced by farm and age at sampling. Heifers born to dams that were not being milked during gestation had lower AMH and AFC compared with offspring of cows on their first lactation, whereas no difference was detected between offspring of cows on their first and subsequent lactations. Summer and winter heifers had similar age at first service and at first calving, and similar number of services per conception. Regardless of season in early fetal life, heifers were classified into 3 groups based on AMH and AFC (low = 20%, intermediate = 60%, high = 20%). Heifers with the lowest AMH were older at first service compared with herd mates with intermediate AMH, but age at first calving and number of services per conception were similar among AMH categories. No difference was detected in any of the fertility measures among AFC categories. Heifers born to mothers exposed to high environmental temperatures in early gestation had smaller ovarian reserves compared with herd mates conceived in winter, but no association between season of early fetal life and fertility at first conception was established. Season of conception and maternal lactation status affect the size of the ovarian reserve, but not fertility, at first conception in the progeny.

203 High environmental temperatures during early fetal life may impair the ovarian reserve in cattle

The causes of the inherently high variation in number of follicles and oocytes in ovaries of mammals are unknown. Evidence suggests that the ovarian reserve (total number of healthy follicles and oocytes in ovaries) can be programmed by events occurring during fetal life. For instance, maternal nutritional restriction during the first trimester of pregnancy negatively affects the size of the ovarian reserve in calves. The aim of the present study was to establish whether exposure of pregnant dairy cows to high environmental temperatures from conception to the end of the first trimester of pregnancy impairs establishment of the ovarian reserve in their offspring. This work was conducted in four commercial dairy farms with similar nutrition and farming systems located in Sardinia, Italy, on a total of 310 Holstein-Friesian dairy heifers (16 months old) that were conceived and born at different times of year coincident with different environmental temperatures. We tested whether exposure of the heifer's dams to a mean temperature-humidity index (THI) >68 from conception to the end of the first trimester of pregnancy resulted in a diminished ovarian reserve in their offspring. To estimate the size of the ovarian reserve, a single blood sample was collected to measure serum anti-Müllerian hormone (AMH; n=310), and the number of follicles >3mm (antral follicle count, AFC) was assessed using transrectal ovarian ultrasonography (n=258) on a random day of the oestrous cycle (16.09±0.07 months of age). Relations among variables were analysed with Pearson correlation with SAS (SAS Institute Inc.). Anti-Müllerian hormone and AFC were analysed with a mixed model (PROC MIXED of SAS) considering the main effects of season during the first trimester of fetal life and age at sampling; the effect of farm was included as a random effect. Tukey's test was used for comparisons. Circulating AMH concentrations and AFC were highly positively correlated (P<0.0001), as previously reported. The results also showed that both AMH concentrations and AFC were lower (419.27±22.81 pgmL−1, 9.32±0.42 follicles; P<0.0001) in young adult heifers of the dams exposed to a THI >68 compared with dams exposed to an average THI of 55 (634.91±47.60 pgmL−1, 11.84±0.46 follicles). Neither AMH nor AFC were influenced by farm and age at sampling of the daughters. In conclusion, maternal exposure to THI >68 (typical high temperatures during summers in Sardinia) during the first trimester of pregnancy has a negative effect on the development of the ovarian reserve in female fetuses, which may subsequently impair their reproductive performance as adults. Research was funded by Regione Autonoma della Sardegna, Legge Regionale 7, Bando 2015.

Tubulin posttranslational modifications in in vitro matured prepubertal and adult ovine oocytes

Microtubules (MTs), polymers of alpha/beta-tubulin heterodimers, are involved in crucial functions in eukaryotic cells. MTs physiology can be influenced by a variety of post-translational modifications (PTMs), including tyrosination, detyrosination, delta 2 modification, acetylation, polyglutamylation, polyglycylation. In mammalian oocytes, MTs are essential for meiosis, regulating the formation of meiotic spindle and chromosomes movements. Considering that the patterns of tubulin PTMs (tyrosination, detyrosination, acetylation, polyglutamylation and delta 2 modification) have not been investigated in ovine oocytes, this study has been designed to investigate their presence and quantification in in vitro matured (IVM) adult and prepubertal ovine oocytes. Oocytes from adult and lamb Sarda ewes, regularly slaughtered at the local abattoir, were in vitro matured, fixed, and processed by indirect immunofluorescence and confocal microscopy analyses at metaphase II stage. Our results revealed a well detectable signal for total, tyrosinated and acetylated α-tubulin in meiotic spindle of both sheep and lamb oocytes. On the other hand, no immunopositivity were appreciable for detyrosinated, polyglutamylated, and delta 2 tubulin in meiotic spindle of both sheep and lamb oocytes. As regard the tyrosinated and the acetylated α-tubulin PTMs, through the quantification of the fluorescence intensity, we did not find significant differences in their expression in meiotic spindle of sheep, while in lamb the acetylated tubulin levels were predominant in comparison with tyrosinated. Our results in addition to investigating for the first time the different tubulin PTMs in the spindle organization of ovine oocytes, showed a different microtubule pattern between adult and prepubertal oocytes. The microtubule cytoskeleton survey may thus suggest further cues to better understand skill-related problems in in the acquisition of oocyte competence.

Glucogenic treatment creates an optimal metabolic milieu for the conception period in ewes

This study determined the influence of a short-term glucogenic nutritional treatment on circulating concentrations of glucose, insulin, insulin-like growth factor 1 (IGF-1), nonesterified fatty acids (NEFA), and urea, and on their correspondent levels in follicular fluid (FF) collected 12 h after the end of the treatment. After estrous synchronization with intravaginal progestagen-impregnated sponges, 20 Sarda ewes were randomly allocated into two experimental groups (GLU and WAT) and, from day 7 to day 10 (day 0 = day of sponge removal), the GLU group was gavaged with a glycogenic mixture, whereas the WAT group was gavaged with water (control group). Follicular development was stimulated by FSH administration from day 8 to 10. At day 11, ovaries were collected and follicular fluid processed. Plasma changes were assessed from day 6 to 11. In GLU group, circulating concentration of glucose (P < 0.0001), insulin (P < 0.0001), and IGF-1 (P < 0.01) rose significantly, whereas NEFA and urea concentrations decreased (P < 0.0001), as compared with controls. In particular, in FF the higher glucose concentrations found in GLU ewes compared with controls (P < 0.0001) were not accompanied by any increase in insulin and IGF-1 concentrations. NEFA (P < 0.0001) and urea (P < 0.0001) were lower in FF of GLU than WAT group, although NEFA clearance in the ovary proved to be less efficient than at the systemic level. No significant difference between groups was found in FF concentrations of pregnancy-associated plasma protein A (a protease regulating the levels of free IGF-1 in follicles), glutathione, and in its total antioxidant capacity. These results suggest that glycogenic mixture administration creates a suitable follicular microenvironment for the conception period in dairy ewes.

Glucogenic supply increases oocyte developmental competence in sheep

The present study aimed to determine the influence of a glucogenic supply on oocyte developmental competence. Oestrous cycles were synchronised in 22 Sarda ewes by the insertion (Day 0) of one intravaginal progestagen-impregnated sponge that was removed after 6 days. After removal, the ewes were randomly allocated into two experimental groups (treated and control ewes) and, from Day 7 to Day 11, treated ewes received oral administration of a glucogenic mixture, whereas control animals received water. Follicular development was stimulated by FSH administration from Days 8 to 10. Glucose metabolism was assessed from Days 7 to 11, whilst follicle and corpus luteum growth dynamics and functionality were evaluated between Days 6 and 11. At Day 11 ovaries were collected and processed for in vitro embryo production. Glucogenic treatment increased both the plasma levels of glucose, progesterone, oestradiol and the number of 2-3-mm follicles (P < 0.05). Higher fertilisation and blastocyst rates (P < 0.05) were obtained after IVM of oocytes recovered from treated ewes compared with control ones. In conclusion, glucogenic treatment modifies follicle and corpus luteum functionality and improves oocyte quality, as evaluated by in vitro developmental kinetics and blastocyst output.

Effect of "ice blockers" in solutions for vitrification of in vitro matured ovine oocytes

Polymers have been used as a substitute for serum in vitrification solutions for embryos and oocytes. This study was designed to replace serum with defined commercial macromolecules in vitrification solution for in vitro matured ovine oocytes. Oocytes were cryopreserved in two vitrification solutions (16.5 percent ethylene glycol + 16.5 percent dimethyl sulphoxide) supplemented with 1 percent of SuperCool X-1000 and 1 percent SuperCool Z-1000 (Ice Blockers) or 20 percent foetal calf serum (FCS). After warming, oocytes viability and developmental potential after processing for in vitro embryo production were assessed. The number of viable oocytes (87.4 percent and 85.9 percent), cleaveage rates (21.4 percent and 19.6 percent) and blastocyst development rates (4.8 percent and 4.5 percent) were similar for Ice Blockers and FCS, respectively. On the basis of these findings, it may be concluded that combined use of Ice Blockers (SuperCool X-1000 and SuperCool Z-1000) as supplementation in vitrification solution offers similar results to serum for vitrification of in vitro matured ovine oocytes.

Differences in semen freezability and intracellular ATP content between the rooster (Gallus gallus domesticus) and the Barbary partridge (Alectoris barbara)

This study aimed to compare viability, ATP content, and DNA integrity of rooster (Gallus gallus domesticus) and Barbary partridge (Alectoris barbara) fresh and frozen spermatozoa in order to identify factors possibly related to differences in semen freezability. Ejaculates were obtained from March to May by the abdominal massage method from 3 adult roosters and 12 adult Barbary partridges. Semen was frozen with different cryoprotectants using Lake's diluents as a base medium: 1) glycerol 11%; 2) glycerol 11% and trehalose 70 mmol/L; 3) dimethylacetamide (DMA) 6%; 4) DMA 6% and trehalose 70 mmol/L. Both fresh and frozen semen showed a lower viability and higher intracellular ATP concentrations in the Barbary partridge compared with the rooster (P < 0.05). In the Barbary partridge, semen viability after thawing did not differ among the 4 media used, but glycerol showed positive effects in avoiding a significant loss of ATP after thawing, compared with DMA containing media (P < 0.05). On the other hand, in the rooster a higher viability was recorded when semen was frozen in glycerol containing media compared to DMA (P < 0.0001), while ATP values significantly decreased after thawing (P < 0.05) without showing any differences among the semen frozen in the 4 different media. DNA integrity, as evaluated by the comet assay, was assessed only in frozen semen. In the Barbary partridge, mean scored parameter did not differ significantly among semen frozen in the 4 different media. In the rooster DNA fragmentation was higher in DMA ctr medium compared with the other media and with values found in Barbary partridge semen frozen in the same medium (P < 0.001). In both species, the addition of trehalose did not show any positive effects on viability, ATP levels and DNA integrity after thawing. In conclusion, species-related differences in semen features exist between the rooster and the Barbary partridge and the wide variation observed in ATP levels may account for differences in semen freezability between the two species.

In vitro oocyte maturation, fertilization and culture after ovum pick-up in an endangered gazelle (Gazella dama mhorr)

The recovery of immature oocytes followed by in vitro maturation, fertilization and culture (IVMFC) allows the rescue of biological material of great genetic value for the establishment of genetic resource banks of endangered species. Studies exist on sperm cryopreservation of endangered Mohor gazelle (Gazella dama mhorr), but no work has been carried out yet on oocyte collection, fertilization and culture in this or related species. The purpose of this study was to develop a protocol for ovarian stimulation for the recovery of oocytes and subsequent IVMFC in the Mohor gazelle using frozen-thawed spermatozoa. Ovum pick-up was performed after ovarian stimulation with a total dose of 5.28 mg of ovine FSH. A total of 35 oocytes were recovered from 56 punctured follicles (62%) (N=6 females). Out of 29 cumulus-oocyte complexes matured in vitro, 3% were found at germinal vesicle stage, 7% at metaphase I, 21% were degenerated, and 69% advanced to metaphase II. Fertilization and cleavage rates of matured oocytes were 40 and 30%, respectively. Embryos cleaved in vitro up to the 6-8 cell stage but none progressed to the blastocyst stage, suggesting the existence of a developmental block and the need to improve culture conditions. Although more studies are needed to improve hormonal stimulation and oocyte harvesting, as well as IVMFC conditions, this study demonstrates for the first time the feasibility of in vitro fertilization with frozen-thawed semen of in vitro matured oocytes collected by ovum pick-up from FSH-stimulated endangered gazelles.

Morphological and biochemical analysis of immature ovine oocytes vitrified with or without cumulus cells

The cryopreservation of oocytes is an open problem as a result of their structural sensitivity to the freezing process. This study examined (i) the survival and meiotic competence of ovine oocytes vitrified at the GV stage with or without cumulus cells; (ii) the viability and functional status of cumulus cells after cryopreservation; (iii) the effect of cytochalasin B treatment before vitrification; (iv) chromatin and spindle organization; (v) the maturation promoting factor (MPF) and mitogen-activated protein kinase (MAPK) activity of vitrified oocytes after in vitro maturation. Sheep oocytes were vitrified at different times during in vitro maturation (0, 2, and 6 h) with (COCs) or without cumulus cells (DOs). After warming and in vitro maturation, oocytes denuded at 0 h culture showed a significantly higher survival and meiotic maturation rate compared to the other groups. Hoechst 33342/propidium iodide double staining of COCs and microinjection of Lucifer Yellow revealed extensive cumulus cell membrane damage and reduced oocyte-cumulus cell communications after vitrification. Cytochalasin B treatment of COCs before vitrification exerted a negative effect on oocyte survival. After in vitro maturation, the number of vitrified oocytes with abnormal spindle and chromatin configuration was significantly higher compared to control oocytes, independently of the presence or absence of cumulus cells. The removal of cumulus cells combined with vitrification significantly decreased the MPF and MAPK levels. This study provides evidence that the removal of cumulus cells before vitrification enhances oocyte survival and meiotic competence, while impairing the activity of important proteins that could affect the developmental competence of oocytes.

Effects of trehalose co-incubation on in vitro matured prepubertal ovine oocyte vitrification

Our aim was to evaluate if loading prepubertal ovine oocyte with trehalose would impact on their further developmental potential in vitro and if it would improve their survival to vitrification procedures. COCs matured in vitro with (TRH) or without (CTR) 100mM trehalose were tested for developmental potential after in vitro fertilization and culture. Trehalose uptake was measured by the antrone spectrophotometric assay. No differences were recorded between the two experimental groups in fertilization rates (91.1 CTR vs 92.5% TRH), cleavage rates calculated on fertilized oocytes (96.1 CTR vs 95.4% TRH), first cleavage kinetic (56.1 CTR vs 51% TRH), and blastocyst rates (14.3 CTR vs 13.0% TRH). Anthrone assay revealed that in TRH group trehalose concentration/oocyte was 2.6microM. MII oocytes were then vitrified using cryoloops in TCM 199 containing 20% FCS, sucrose 0.5M, 16.5% Me(2)SO, 16.5% EG and plunged in LN(2). After warming, oocytes from TRH and CTR groups were tested for membrane integrity using the propidium iodide (PI)/Hoechst differential staining, and for developmental ability after in vitro fertilization. Trehalose in maturation medium affected membrane resistance (P<0.01) to vitrification/warming but not fertilization and cleavage rates. The differential staining showed a lower number of PI positive cells in TRH group compared to CTR one (14.3 vs 24.7%, respectively). Fertilization rates and cleavage rates did not differ between the two groups (55.3 and 41% for TRH and 47.7 and 41.7% for CTR, respectively). In conclusion trehalose in maturation medium stabilizes cell membranes during vitrification/warming of prepubertal ovine oocytes but does not affect fertilization and cleavage rates after warming.

Effect of vitrification solutions and cooling upon in vitro matured prepubertal ovine oocytes

The vitrification procedure effects on molecular and cytoskeletal components and on developmental ability of in vitro matured prepubertal ovine oocytes were evaluated. MII oocytes were divided into three groups: (1) vitrified in cryoloops (VTR); (2) exposed to vitrification solutions and rehydrated without being plunged into liquid nitrogen (EXP); (3) without further treatment as a control (CTR). Two hours after treatment, membrane integrity, assessed by propidium iodide/Hoechst staining, was lower in VTR and EXP than in CTR (70.6%, 88.5% and 95.2%, respectively). Cleavage rate after fertilization was statistically different among all groups (21.4%, 45.4% and 82.8% for VTR, EXP and CTR groups respectively; P<0.01). Blastocyst rate in VTR (0.0%) and EXP (2.8%) groups was lower (P<0.01) than in CTR (22.8%). Maturation promoting factor activity was lower (P<0.01) in VTR and EXP groups compared with CTR at both 0 h (82.2%, 83.6% and 100%, respectively) and 2 h (60% and 53.9% and 100%, respectively) after warming. Immediately after warming VTR and EXP oocytes showed a lower rate of normal spindle and chromosome configuration compared to CTR (59.1%, 48.0% and 83.3%, respectively; P<0.01). After 2 h of culture in standard conditions the percentage of oocytes with normal spindle and chromosome organization decreased in both VTR and EXP groups compared to CTR (36.4%, 42.8% versus 87.5%, respectively). In conclusion the exposition to the tested cryoprotectant solution and the vitrification in cryoloops modified cytoskeletal components and alter biochemical pathways that compromise the developmental capacity of prepubertal in vitro matured ovine oocytes.

A Low Oxygen Atmosphere during IVF Accelerates the Kinetic of Formation of In Vitro Produced Ovine Blastocysts

Among the factors that affect in vitro embryo development, oxygen atmosphere is considered to be of great influence. In this study, we evaluated the influence of two different oxygen atmospheres during in vitro fertilization (IVF) of ovine oocytes on their developmental capacity and quality assessed by cryotolerance. Cumulus oocyte complexes derived from ovaries of slaughtered sheep were matured in vitro and subsequently fertilized under low (5%) or high (20%) oxygen atmospheres, and cultured in SOF + aa + 0.4% BSA in 5% CO2 and 5% O2 up to blastocyst stage. The cleavage rates obtained in the fertilization system at 20% O2 were significantly higher than those obtained in the 5% O2 fertilization system (61.2% vs 50.8%; p < 0.01). The distribution of cleaved oocytes at 22, 26 and 40 h of culture intervals was not different in the low or high O2 atmosphere (31.4%, 26.4% and 42.1% vs 28.0%, 29.3% and 42.7% respectively). Blastocysts output on the 6th day post-fertilization (dpf) was significantly higher when oocytes were fertilized under 5% O2 concentration (63.04% in 5% O2 vs 47.36% in 20% O2), while on the 7th dpf the higher number of blastocysts was obtained in the 20% O2 system (35.10%.in 20% O2 vs 26.09% in 5% O2). After vitrification no differences were observed between low or high oxygen atmosphere in the viability rates of blastocysts obtained on day 6 (93.6% vs 96.5%), on day 7 (46.3% vs 41.7%) and on day 8 (11.1% vs 6.6%). After differential staining, no significant differences were observed in the total cell number and inner cell mass and trophoblastic cells ratio of blastocysts produced on 6 dpf (189.6 +/- 51.3 and 0.260 +/- 0.07 vs 223.3 +/- 45.6 and 0.277 +/- 0.09), on 7 dpf (168.3 +/- 25.1 and 0.316 +/- 0.06 vs 172.1 +/- 33,6 and 0.320 +/- 0.06) and on 8 dpf (121.2 +/- 23,8 and 0.302 +/- 0.03 vs 117.0 +/- 35.1 and 0.313 +/- 0.04) under low or high oxygen atmosphere respectively). In conclusion, our data suggest that low oxygen atmosphere during IVF affects positively the production of high quality ovine blastocysts.

Cannabinoid CB1 receptors in the paraventricular nucleus and central control of penile erection: Immunocytochemistry, autoradiography and behavioral studies

[N-(piperidin-1-yl)-5-(4-chlorophenyl)-4-methyl-1H-pyrazole-3-carboxyamide] (SR 141716A), a selective cannabinoid CB1 receptor antagonist, injected into the paraventricular nucleus of the hypothalamus (PVN) of male rats, induces penile erection. This effect is mediated by the release of glutamic acid, which in turn activates central oxytocinergic neurons mediating penile erection. Double immunofluorescence studies with selective antibodies against CB1 receptors, glutamic acid transporters (vesicular glutamate transporters 1 and 2 (VGlut1 and VGlut2), glutamic acid decarboxylase-67 (GAD67) and oxytocin itself, have shown that CB1 receptors in the PVN are located mainly in GABAergic terminals and fibers surrounding oxytocinergic cell bodies. As GABAergic synapses in the PVN impinge directly on oxytocinergic neurons or on excitatory glutamatergic synapses, which also impinge on oxytocinergic neurons, these results suggest that the blockade of CB1 receptors decreases GABA release in the PVN, increasing in turn glutamatergic neurotransmission to activate oxytocinergic neurons mediating penile erection. Autoradiography studies with [(3)H](-)-CP 55,940 show that chronic treatment with SR 141716A for 15 days twice daily (1 mg/kg i.p.) significantly increases the density of CB1 receptors in the PVN. This increase occurs concomitantly with an almost twofold increase in the pro-erectile effect of SR 141716A injected into the PVN as compared with control rats. The present findings confirm that PVN CB1 receptors, localized mainly in GABAergic synapses that control in an inhibitory fashion excitatory synapses, exert an inhibitory control on penile erection, demonstrating for the first time that chronic blockade of CB1 receptors by SR 141716A increases the density of these receptors in the PVN. This increase is related to an enhanced pro-erectile effect of SR 141716A, which is still present 3 days after the end of the chronic treatment.

Effects of progestagens on follicular growth and oocyte developmental competence in FSH-treated ewes

Previous research has reported evidence for negative effects of progestagens on follicular growth and oocyte competence. In the present study, negative effects of progestagens on follicular growth and oocyte developmental competence were assessed. During the breeding season, 20 Sarda ewes were treated with two doses of cloprostenol, 10 days apart, to assure the presence of a corpus luteum (CL). On day 5 after the second cloprostenol dose, 10 ewes were treated with a progestagen sponge while 10 females remained untreated. Starting on day 7 after the second cloprostenol dose, all the ewes were treated with 6 equal doses of 24 I.U. of FSH (Ovagen, ICP, NZ), every 12h. The number of follicles > or =2mm in diameter increased (P<0.0005) in all the ewes from 24 h before to 60 h after the first FSH dose (from 12.8+/-1.1 to 23.4+/-1.3 in treated and from 12+/-0.6 to 22+/-1.2 in untreated ewes, n.s.). There were no significant differences in follicle dynamics between groups, but concentrations of estradiol in control ewes were higher than in the progestagen group (P<0.05). Twelve hours after the last FSH dose, oocytes were collected by ovum pick-up. Recovery rates were lower for progestagen-treated ewes (71.1 versus 83%; P<0.001). After IVP procedure, cleavage rate was also lower in the progestagen group (39.1 versus 82.6%; P<0.001). Furthermore, blastocysts output revealed that oocyte developmental competence was lower in progestagen group (17.3 versus 30.4%; P=0.245), although differences were not significant. These results suggest deleterious effects from progestagen on oocyte developmental competence and set the basis for new protocols for in vitro embryo production.

Cryopreservation of European Mouflon (Ovis Gmelini Musimon) Semen During the non-Breeding Season is Enhanced by the Use of Trehalose

The influence of trehalose on European mouflon spermatozoa cryopreservation during the non-breeding season was tested. Semen was frozen in two different extenders: (a) recommended Tris-based ram extender (CTR); (b) CTR extender supplemented with trehalose 0.147 mm (TRH). Sperm viability and acrosome integrity were assessed using propidium iodide and fluorescein isothiocynate labelled Pisum Sativum agglutinin. Trehalose significantly enhanced sperm viability after thawing compared with CTR extender (62.7% vs 51.8%; p < 0.05), whereas no differences were observed on acrosome integrity (42.9% vs 42.1%). Trehalose influence was also evidenced in the in vitro fertility test performed with sheep oocytes matured in vitro. Both fertilization rates (60.9% TRH vs 43.6% CTR; p < 0.05) and cleavage rates (58% TRH vs 39.8% CTR; p < 0.001) were higher for trehalose frozen semen compared with control extender frozen semen. A higher percentage of zygotes resulting from fertilization with trehalose cryopreserved semen presented the first cleavage earlier if compared with the group fertilized with control semen (48.7% vs 31.5%, respectively; p < 0.01). This result was confirmed by embryo kinetic development. Fertilization with trehalose cryopreserved semen leaded to an higher percentage of blastocysts (40.2% vs 27.8% CTR; p < 0.05), and enhanced in particular the number of blastocysts that developed on the day 6th of culture (28.6% vs 17% CTR; p < 0.05). Our data demonstrated that, during mouflon non-breeding season, trehalose extender enhances spermatozoa viability and its in vitro fertilizing capacity, allowing the production of an higher number of blastocysts.

108 EFFECT OF CAFFEINE TREATMENT ON MPF AND MAPK ACTIVITY AND PARTHENOGENETIC ACTIVATION OF VITRIFIED MII OVINE OOCYTES

Cryopreservation of oocytes is still an open problem because of their structural sensitivity to the cooling and freezing process. Meiotic spindle disorganization and chromosomal aberrations are frequently observed, possibly due to the alteration of molecules involved in the meiotic cell cycle regulation and spindle formation such as maturation promoting factor (MPF) and mitogen-activated protein kinase (MAPK). In this study we treated MII ovine oocytes with caffeine before vitrification and we evaluated the effect on (1) MPF and MAPK activity and (2) oocyte spontaneous or induced parthenogenetic activation. Oocytes from slaughterhouse sheep ovaries were in vitro-matured for 21 h in TCM-199 + 10% FCS + FSH, LH + cysteamine, and then incubated for 2 h with (+) or without (-) caffeine (20 mM; Sigma-Aldrich, Milan, Italy). Thereafter, MII oocytes were vitrified by equilibration with 10% ethylene glycol (EG) + 10% DMSO (30 s), exposure to 20% EG + 20% DMSO + 0.5 M sucrose (20 s), loading onto the Cryotop, and plunging into liquid nitrogen. After warming, groups of (+) and (-) oocytes were used for MPF and MAPK assays or (A) cultured in TCM-199 + 10% FCS for 24 h to evaluate spontaneous parthenogenetic activation, or (B) activated with ionomycin (5 �M, 5 min; Sigma) and cultured as in A. Fresh (+) and (-) oocytes were processed as above as controls. All oocytes were stained with glycerol-Hoechst 33342 to evaluate chromatin configuration. After vitrification, similar rates of spontaneous parthenogenetic activation between (+) and (-) oocytes (12/38, 31.6% vs. 16/38, 42.1%, respectively) were observed. However, the number of oocytes with a regular chromatin configuration in the MII plate was significantly higher (P &lt; 0.01; chi-square test) in vitrified (+) compared to (-) oocytes (22/38, 57.9% vs. 4/38, 10.5%, respectively). After incubation with ionomycin, a significantly (P &lt; 0.05) lower proportion of activated oocytes was recorded in the (+) compared to the (-) group (19/49, 38.8% vs. 32/53, 60.4%, respectively). In the control oocytes, the treatment with caffeine significantly (P &lt; 0.01) decreased the activation rate after ionomycin stimulation compared to that of non-caffeine-treated control oocytes (6/51, 11.8% vs. 28/46, 60.9%, respectively), but no difference in spontaneous parthenogenetic activation was found between (+) and (-) groups (6/38, 15.8% vs. 6/46, 13.0%, respectively). Analysis of MPF and MAPK activities showed that caffeine treatment significantly increased (P &lt; 0.05; ANOVA) the levels of the 2 kinases of vitrified MII oocytes, and these values are comparable to those of MII fresh oocytes. These results show that caffeine can increase MPF and MAPK activity in vitrified ovine oocytes and thus may contribute toward maintaining a regular chromatin organization in the MII plate and toward the decrease in parthenogenetic iomomycin-induced activation. Experiments are in progress to test the efficiency of caffeine treatment to improve the development competence of vitrified MII ovine oocytes.

Vitrification devices affect structural and molecular status of in vitro matured ovine oocytes

We evaluated the effect of three different cryodevices on membrane integrity, tubulin polymerization, maturation promoting factor (MPF) activity and developmental competence of in vitro matured (IVM) ovine oocytes. IVM oocytes were exposed during 3 min to 7.5% DMSO and 7.5% ethylene glycol (EG) in TCM199 and 25 sec to 0.5 M sucrose, 16.5% DMSO and 16.5% EG, loaded in open pulled straws (OPS), cryoloops (CL) or cryotops (CT) and immersed into liquid nitrogen. Untreated (CTR) or exposed to vitrification solutions but not cryopreserved (EXP) oocytes were used as controls. After warming, double fluorescent staining evidenced a lower membrane integrity in vitrified groups compared to the controls (P < 0.01). After in vitro fertilization and culture OPS and CL groups evidenced a lower cleavage rate than CT and controls (P < 0.01) while blastocysts were obtained only in CL and EXP, at a lower rate than CTR (P < 0.01). All vitrified groups showed alterations in spindle conformation, which were partially recovered in OPS and CT groups. MPF activity was lower in treated compared to CTR and CT showed the lowest value (P < 0.01). After 2 hr culture MPF activity was restored in all groups except CT. Parthenogenetic activation was higher in treated compared to CTR and CT evidenced the highest value. Our results indicate that cryodevice influences not only the ability to survive cryopreservation but is also associated with molecular alterations which affect developmental competence.

A new selection criterion to assess good quality ovine blastocysts after vitrification and to predict their transfer into recipients

The feasibility to accurately select viable embryos would be valuable for improving pregnancy rates and avoiding futile transfer attempts. The aim of our study was to assess if in vitro-produced embryo quality could be determined by the timing of blastocoelic cavity re-expansion after vitrification, warming, and in vitro culture using sheep as a model. Blastocysts were produced in vitro, vitrified/warmed, and cultured in TCM-199 plus 10% FCS for 72 hr. Embryos were divided into two groups: re-expanded within 8 hr (A) and from 8 to 16 hr (B) of IVC after warming. Fast re-expanded blastocysts showed higher in vitro hatching rates and total cell number calculated on the hatched blastocysts compared with slow re-expanded ones (P < 0.01). Peroxide status evaluation (P < 0.01) and TUNEL test (P < 0.05) revealed a higher number of positive cells in group B compared with group A. The quantitative analysis of protein synthesis revealed a higher synthesis in fast compared with slow re-expanded embryos (P < 0.05). Quantitative RT-PCR showed that 90-kDa Heat Shock Protein beta was more expressed in group A than in group B (P < 0.05), while the quantity of P34(cdc2), Cyclin b, Aquaporin 3, Na/K ATPase, and Actin did not differ between the two groups. Pregnancy rates after transfer to synchronized recipients were higher in fast compared to slow re-expanded blastocysts (P < 0.05). Our results evidenced that timing of blastocoelic cavity re-expansion after vitrification/warming and in vitro culture can be considered as a reliable index of in vitro produced embryo quality and developmental potential.

258 EXPRESSION PATTERN OF THE MATERNAL FACTOR ZYGOTE ARREST 1 (ZAR1) GENE IN OVINE OOCYTES AND PRE-IMPLANTATION EMBRYOS

Zygote arrest 1 (ZAR1) is an ovary-specific maternal factor that plays essential roles during the oocyte-to-embryo transition. It is evolutionary conserved in vertebrates, and the protein is characterized by the presence of a homeobox zing finger domain, suggesting its role in transcription regulation. Discovered in mice (Wu et al. 2003 Nat. Genet. 33, 187-191), its expression pattern has been analyzed in oocytes and pre-implantation embryos in mice, cattle, and pig (Pennetier et al. 2004 Biol. Reprod. 71, 1359-1366; Brevini et al. 2004 Mol. Reprod. Dev. 69, 375-380; Reprod. Biol. Endocrinol. 21, 4-12). Because no information on Zar1 ortholog in the ovine species is available, the aim of this study was to assess its presence and to analyze its expression pattern in oocytes and pre-implantation embryos. Reverse transcription-polymerase chain reaction (RT-PCR) was performed in germinal vesicle (GV) and IVM metaphase II (MII) oocytes, and, following IVFC, in 2- (2C), 4- (4C), 8- (8C), and 12-16- (12C-16C) cell embryos, morulae, and blastocysts. Primers were designed on the basis of bovine and swine conserved sequences and contained an intron-spanning region. The PCR product was sequenced and the alignment, performed with BLAST (www.ncbi.nlm.nih.gov/BLAST/), confirmed its homology with the Zar1 orthologous genes present in public databases, sharing 98%, 92%, and 89% nucleotide identity with the bovine, porcine, and human sequences, respectively. Real-time PCR revealed that Zar1 is present at its highest level in the GV oocyte, has a major decrease at the MII stage (around 10-fold), remains constant in the embryo first cleavage steps (2C-4C), drops again at the 8C stage (around 30-fold), and disappears in morulae and blastocysts. Our data demonstrate that a Zar1 ortholog is present in the ovine species. Results are also in accordance with the expression patterns characterized in other mammalian species and suggest that Zar1 transcript in the ovine oocyte may be necessary for normal female reproduction in the transition from oocyte to embryonic life.

GnRH antagonist enhance follicular growth in FSH-treated sheep but affect developmental competence of oocytes collected by ovum pick-up

This study evaluates the in vitro developmental competence of oocytes collected by ovum pick up (OPU) from sheep treated with GnRH antagonists (GnRHa) and high doses of FSH. Eighteen Sarda ewes were treated with progestagen sponges (day 0). On day 7, 10 ewes received 3 mg of GnRHa s.c., while 8 served as control receiving saline. On day 10, all animals were treated with 96 IU of ovine FSH in four equal doses given i.m. every 12 h. We monitored follicular development by ultrasonography, twice daily from day 7 to 11, and found that GnRHa induced a significant increase in the number of total follicles in 72 h (11.7+/-0.9 to 21+/-2.4, r(2)=0.598, P<0.0001), while this number remained stable in control sheep. We found that FSH induced a significant rise in the number of follicles in both groups; but always higher (P<0.05) in GnRHa treated sheep, confirming that GnRHa enhances ovarian response to exogenous FSH stimulation. Twelve hours after the last FSH dose, oocytes were collected by OPU. Recovery percentage, morphological quality, ability to resume meiosis, fertilization and cleavage were similar in oocytes from treated and untreated sheep. However, the final blastocysts output was lower in GnRHa group (10.1% versus 27.4% in control group; P<0.05). In addition, re-expansion rates after vitrification, thawing and in vitro culture were lower in GnRHa treated ewes, although differences did not reach statistical significance (55.5% versus 74.1% in GnRHa treated and in control sheep, respectively).

Relations between relative mRNA abundance and developmental competence of ovine oocytes

The present study was conducted to investigate the relation between in vitro developmental competence and the expression of a panel of developmentally important genes in germinal vesicle (GV) stage oocytes. One-month-old prepubertal and adult sheep oocytes were used as models of low and high quality gametes, respectively. Cumulus-oocyte complexes (COCs) derived from lambs and ewes were in vitro matured and fertilized, and their cleavage rate at 22, 26, and 32 hr post fertilization and the blastocyst yield were observed to assess their developmental potential. In parallel, the relative abundance (RA) of 11 genes was analyzed by semi-quantitative Reverse Transcription Polymerase Chain Reaction (RT-PCR) assay in the two groups of oocytes. We observed similar maturation and fertilization rates in the two groups, but a significant lower rate of cleaved prepubertal oocytes (P < 0.05), a general delay in the timing of their first division (P < 0.01), and a lower blastocysts production (P < 0.05). The analysis of gene expression evidenced no difference in the RA of four transcripts [superoxide dismutase (SOD), ubiquitin, beta-actin, cyclin B] in the two classes of oocytes, but a statistically lower RA of seven messenger RNAs (mRNA) [Na(+)K(+)ATPase, p34(cdc2), Glucose-transporter I (Glut-1), Activin, Zona Occludens Protein 2 (PanZO2), Poli(A)Polymerase (PAP), E-Cadherin (E-Cad)] in the prepubertal oocytes compared to the adult ones. The present data show for the first time in the ovine species that the lower developmental competence is associated with deficiencies in the mRNAs storage during the oocyte growth.

230 IN VITRO MATURATION OF OOCYTES FROM ENDANGERED DORCAS GAZELLE (GAZELLA DORCAS NEGLECTA)

In vitro maturation of oocytes recovered from dead animals provides an opportunity for rescuing genetic material for biodiversity conservation. The dorcas gazelle (Gazella dorcas) is regarded by the World Conservation Union (IUCN) as ‘vulnerable’ but the subspecies G. dorcas neglecta is thought to be endangered due to excessive hunting. A captive breeding program for dorcas gazelles has been developed at the Estacion Experimental de Zonas Aridas (CSIC) in the South of Spain where efforts have so far concentrated on natural breeding and on the development of sperm cryopreservation protocols. The aim of the present study was to explore the possibility of recovering and maturing in vitro healthy oocytes from animals that die suddenly for the establishment of a program to rescue female gametes. Ovaries of a dorcas female that died unexpectedly were collected about 7 h after death of the animal. Cumulus–oocyte complexes (COCs) were recovered by slicing the ovaries. Collection and washing of COCs were performed in warmed TCM-199-HEPES with antibiotics and polyvinyl alcohol. Degenerated oocytes or those with expanded cumulus cells were removed. A total of 15 COCs were cultured in TCM-199 with 10% heat-treated fetal calf serum, 10 μg/mL ovine FSH/LH, 1 µg/mL estradiol, and 0.1 mg/mL glutamine at 38.5°C under 5% CO2/air with high humidity. After 24 h of culture, matured oocytes, as revealed by the presence of a polar body, were activated with 7% ethanol for 10 min and further incubation for 3 h. Meiotic progression and activation were evaluated by staining with Hoechst 33342 and propidium iodide (1 μg/mL each) and visualization under a fluorescence microscope. Results at the end of incubations showed that 4/15 oocytes were degenerated, 4/15 were arrested at the MI stage, and 7/15 (46.7%) progressed to the MII stage. One oocyte was found to be at the 2-cell stage but it could not be established whether this was the result of the activation method used. These results demonstrate that it is possible to recover viable oocytes several hours after death and rescue them for subsequent in vitro maturation and fertilization. More studies are needed to characterize suitable conditions for oocyte maturation, fertilization, and culture in the dorcas gazelle. This would, in turn, help in the effort to rescue biomaterials from wildlife for generating offspring. This work was supported by the Spanish Ministry of Education and Science (REN 2003–01587) and Acciones Integradas (HI20030336).

216 IN VITRO OOCYTE MATURATION, FERTILIZATION, AND CULTURE AFTER LAPAROSCOPIC OVUM PICK-UP IN AN ENDANGERED GAZELLE (GAZELLA DAMA MHORR)

The recovery of immature oocytes followed by in vitro maturation, fertilization and culture (IVMFC) allows the rescue of biological material of great genetic value for the establishment of genetic resource banks. Studies have been carried out on endangered Mohor gazelle sperm cryopreservation (Garde et al. 2003 Biol. Reprod. 69, 602-611), but there are no studies on oocytes in this species. The purpose of this work was to develop a protocol for ovarian stimulation for the recovery of oocytes and subsequent IVMFC. The study was conducted using six reproductively mature female Mohor gazelles from the breeding herd at the Estacion Experimental de Zonas Aridas. Animals were synchronized by insertion of controlled progesterone internal drug release (CIDR) devices for 14 days and removal of the devices on the day of ovum pickup (OPU). Follicular growth was stimulated by a total of 5.28 mg of oFSH (Ovagen, ICP, Auckland, New Zealand) given in four equal doses every 12 h. OPUs were performed (Berlinguer et al. 2004 Theriogenology 61, 1477-1486) on Day 15 from the beginning of treatment, and follicles were aspirated with a syringe and a 25G needle using TCM199-HEPES with 50 �g/mL streptomycin, 50 IU/mL penicillin, 0.1% polyvinyl alcohol, and 15 IU/mL heparin. Degenerated oocytes and those with expanded cumulus were removed. Oocytes were cultured in TCM-199 plus 10% FCS, 10 �g/mL ovine FSH/LH, 1 �g/mL estradiol, and 0.1 mg/mL glutamine at 38.5�C under 5% CO2/air and maximum humidity. Spermatozoa were cryopreserved in Tes-Tris with 5% egg yolk and 6% glycerol, and selected by swim-up in SOF medium. After 24 h sperm-oocyte coincubation (sperm concentration: 1 � 106/mL) in SOF with 2% estrus sheep serum under 5% CO2 5% O2 90% N2, presumptive zygotes were transferred to SOF with 0.4% BSA and amino acids under 5% CO2, 5% O2 90% N2 and cultured for 4 days. Oocytes and embryos were stained with Hoechst 33342 and propidium iodide (1 �g/mL each) and visualized under a fluorescence microscope. A total of 35 oocytes were recovered from 56 punctured follicles (62.5%). This recovery rate was similar to those in wildlife in earlier reports, but more studies are needed to improve hormonal stimulation and oocyte harvesting. Out of 29 cumulus-oocyte complexes matured in vitro, 3.5% were found at GV and 6.9% at MI; 20.7% were degenerated and 68.9% had advanced to MII. Fertilization and cleavage rates were 40% and 30%, respectively, of matured oocytes. Out of eight zygotes, six showed cleavage (ranging from 2 to 8 cells). None of the developing embryos progressed to the blastocyst stage, suggesting the existence of a developmental block and the need to improve culture conditions. Although more trials will help to improve IVMFC, this study demonstrates for the first time the feasibility of in vitro fertilization with frozen-thawed semen of in vitro matured oocytes collected by OPU from FSH-stimulated endangered gazelles. This work was supported by the Spanish Ministry of Education and Science (REN 2003-11587) and Acciones Integradas (HI20030336).

110 VITRIFICATION DEVICES AFFECT DEVELOPMENTAL COMPETENCE AND BIOCHEMICAL PROPERTIES OF IVM OVINE OOCYTES

This study was designed to evaluate the effects of 3 different vitrification devices on the developmental ability and on the maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) activity of ovine oocytes in vitro-matured. Cumulus-oocytes complex (COCs) were in vitro-matured in TCM-199 supplemented with 10% FCS, 10 �L/mL of FSH/LH, and 1 �g/mL estradiol at 39�C and 5% CO2 atmosphere. For vitrification, oocytes were incubated in HEPES-buffered TCM-199 containing 20% FCS supplemented with DMSO (7.5%) and ethylene glycol (7.5%). After 3 min, oocytes were loaded into the same medium containing 0.5 m sucrose, 16.5% DMSO, and 16.5% EG, and then immersed into N2 using open pull straw (OPS; Vajta et al. 1998 Mol. Reprod. Dev.), cryoloop (CL; Lane et al. 1999 Nat. Biotechnol.), or cryotop (CT; Kuwayama and Kato 2000 J. Assist. Reprod. Genet.). After warming a part of oocytes were fertilized and cultured in vitro up to blastocyst stage in standard conditions (Leoni et al. 2005 Anim. Reprod. Sci., in press). The fertilization (23.8%, 31.6%, and 36.8% vs. 61.5%) and blastocyst rates (0, 12.5, and 0% vs. 50.0%) were lower for oocytes vitrified in OPS, CL, and CT, compared with control group. Control and vitrified IVM oocytes were valued for MPF and MAPK activity at 0 and 2 h after warming. In both post-warming experimental groups, the MAPK activity did not differ from control group. Immediately post-warming, MPF activity was lower in the vitrified groups compared with control oocytes (P < 0.01). If 100% is assigned to MPF activity in the control oocytes, those in the OPS, CL, and CT groups were, respectively, 63.3%, 65.5%, and 26.2%. After warming and culture for 2 h in standard condition, the activity of MPF was restored to values similar to control oocytes (87.0 and 76.8%, respectively) in the OPS and CL groups, whereas it was at the similar value in the CT group. To evaluate if the lowered MPF activity could cause parthenogenetic activation, the vitrified-warmed oocytes were cultured in SOF + 2% oestrus sheep serum in 5% O2, 5% CO2; after 27 h of culture, the oocytes were fixed and stained with propidium iodide to evaluate chromatin configuration. Results showed significantly higher parthenogenetic activation rates in the CT group compared with OPS and CL groups (54.5% vs. 22.6 and 27.4%, respectively). Our results indicate that the success of cryopreservation of the ovine oocyte is still very limited. The use of different vitrification devices not only modifies the ability to survive cryopreservation and developmental competence of oocytes but is also associated with important molecular alterations in the warmed oocyte cytoplasm. This work was supported by Cofin 2003.

100 TIMING OF BLASTOCOELIC CAVITY RE-EXPANSION REPRESENTS A QUALITY INDEX OF IN VITRO PRODUCED OVINE BLASTOCYSTS

There is general consensus that the quality of in vitro-produced embryos is inferior to that of their in vivo counterparts and that along with other factors this may be responsible for the poorer cryosurvival and the lower pregnancy rates reported for these embryos. The feasibility to accurately select viable embryos would be valuable for improving pregnancy rates and avoiding futile transfer attempts. The aim of our study was to assess whether in vitro-produced ovine embryo quality could be determined by the timing blastocoelic cavity re-expansion after vitrification, thawing, and in vitro culture. Embryos were produced in vitro from ovine ovaries collected at the local slaughterhouse following a standard protocol developed for ovine oocytes, as previously described (Berlinguer et al. 2005 Reprod. Fertil. Dev. 17, 201). Blastocysts were then vitrified/warmed according to a simple method (Leoni et al. 2002 Cryobiology 45, 204-212) and cultured in vitro in TCM-199 supplemented with 10% FCS for 72 h in 5% CO2 in air at 39�C. Vitrified embryos were divided into two groups: (A) expanded within 8 h of in vitro culture after warming; (B) expanded during 8 to 16 h of in vitro culture after warming. Of the 338 vitrified/warmed embryos, 173 (51.1%) showed a re-expanded blastocoelic cavity after 8 h of in vitro culture, whereas 58 (17.1%) re-expanded during 8 to 16 h of in vitro culture. We also analyzed by semiquantitative RT-PCR a panel of genes expressed during pre-implantation embryo development (glucose transporter, HPS-10, e-caderin, poly(A)polimerase, and ubiquitine); our results showed that these genes, apart from ubiquitine which showed no difference in the two groups, were more expressed in Group A blastocysts compared to Group B. Group A blastocysts showed higher hatching rates (67.6%) than Group B blastocysts (43.1%; P < 0.01). The total cell number calculated for the hatched blastocysts after staining with Hoechst 33342 was significantly higher in Group A (140.7 � 8.3, n = 42) than Group B (102.2 � 8.4, n = 27; P < 0.01). Pregnancy rate (detected by ultrasonography 30 days after embryo transfer) after laparoscopic embryo transfer to 12 synchronized recipient Sarda sheep was 40% (6/15) in Group A and 13.4% (2/15) in Group B. The results indicated that timing of blastocoelic cavity re-expansion after vitrification/warming and in vitro culture can be considered as a reliable index of in vitro-produced ovine embryo quality, and in addition, a better prediction for improved survival rate after transfer to synchronized recipients. This work was supported by Cofin 2003.

Induction of the presence of corpus luteum during superovulatory treatments enhances in vivo and in vitro blastocysts output in sheep

This report offers the results of two experiments developed to test possible benefitial effects of the presence of corpus luteum (CL) on in vivo and in vitro sheep embryo production; using two different breeds treated with two different protocols by two different teams at two different centres. In the first trial, estrus was synchronized in 11 ewes with two doses of cloprostenol, 10 days apart. On day 1 after estimated ovulation, sheep were treated with progestagen sponges and superovulated with eight decreasing doses (26.4 units NIH-FSH-S1 x 3, 22.0 units x 2, and 17.6 units x 3) of ovine FSH injected twice daily. Ovulation rate and number of embryos obtained in vivo were compared to those from 12 control ewes without cloprostenol treatment. Presence of a CL improves the number of transferable embryos (7.4+/-0.6 versus 4.1+/-0.6 in control ewes, P < 0.05). The second trial investigated the effects of the presence of CL on embryos produced in vitro from six ewes bearing CL and six ewes without CL at start a superovulatory treatment consisting of 96 units of ovine FSH administered in four equal doses given every 12 h. There were not detected effects of the CL on the number and size of follicles or in the number, morphology and ability to resume meiosis of their oocytes. However, oocytes from ewes with CL showed higher rates of fertilization (73.5 versus 45.5%, P < 0.005), higher development to blastocyst (35.8 versus 19.3%, P < 0.01) and higher hatching rates after vitrification (80.0 versus 25.0%, P < 0.05).

Delay on the in vitro kinetic development of prepubertal ovine embryos

In the present study we characterize the developmental potential of prepubertal and adult ovine oocytes, analyzing the developmental speed to two-cell and blastocyst stages and its relationship with hatching from the zona pellucida, development after vitrification and the number and allocation of inner mass and trophoblastic cells. Prepubertal and adult ovine oocytes were matured and fertilized in vitro and first cleavage rates at 22, 26 and 32 h were recorded. Cleaved oocytes were cultured and blastocyst production was assessed at 6-9 days post-fertilization (dpf). Blastocysts from the two sources obtained on different days were divided into two groups: the first was vitrified, warmed and cultured in vitro to evaluate re-expansion of the blastocoelic cavity; blastocysts of the second were cultured separately to allow for hatching and count of trophoblastic and inner mass cells of hatched blastocysts by differential staining. We observed a significantly lower rate (P < 0.01) of cleaved prepubertal oocytes at 22 and 26 h after fertilization while it was higher (P<0.01) at 32 h than in the adult ones. Adult blastocyst production was significantly lower (P < 0.01) in prepubertal than in adult groups and began on the seventh dpf, later (P < 0.01) than in the adult group, where they appeared on the sixth dpf. Prepubertal blastocysts hatched at a lower rate than the adult ones (P < 0.01) and in both experimental groups faster blastocysts showed a higher (P < 0.01) hatching rate. Similarly, prepubertal derived blastocysts showed lower viability after vitrification (P < 0.01) compared to the adult counterparts, and in particular slower embryos had reduced viability after vitrification compared to the fastest (P < 0.01). Cell number was not different between blastocysts of both groups obtained at 6 and 7 dpf, which were higher (P < 0.01) than those obtained at 8 and 9 dpf. The ICM/trophoblast cell ratio was similar in 6- and 7-day obtained blastocyst and increased (P < 0.01) in those obtained 1 or 2 days later. These findings show that differences in kinetic development between prepubertal and adult derived embryos reflect differences in developmental capacity of the oocytes from which they derive and could be indicative of embryo quality.

101 OVARIAN RESPONSE AND DEVELOPMENTAL COMPETENCE OF OOCYTES COLLECTED BY OPU IN SHEEP TREATED WITH GnRH ANTAGONIST

The use of a single dose of GnRH antagonists during the progestagen treatment prior to superovulatory treatment protocols in sheep increases the number of smaller follicles able to grow and ovulate in response to the exogenous FSH treatment (Lopez-Alonso C et al. 2004 Reprod. Fertil. Dev. 16, 233). The aim of our study was to test if such treatment affects the in vitro developmental competence of oocytes collected by ovum pick up (OPU) from GnRH-antagonist treated sheep during an ovarian by perstimulation protocol. Adult Sarda sheep (n = 18) were synchronized by the insertion of intravaginal sponges (Day 0) which were left in situ for 12 days; on Day 7, group A (n = 10) received a single dose of 3 mg of Antarelix (Teverelix, Europeptides, France) s.c., while group B (n = 8) served as control. All animals received 96 IU of FSH (Ovagen, ICP, New Zealand) administered in 4 equal doses given i.m. every 12 h starting on Day 10. Twelve hours after the last FSH administration oocytes were collected by OPU technique. Follicular growth was monitored by transrectal ultrasonography from Day 7 to Day 11. Collected oocytes were matured, fertilized, and cultured in vitro up to blastocyst stage under standard conditions used in our laboratory (Berlinguer F et al. 2004 Theriogenology 61, 1477–1486). After IVF, uncleaved oocytes were stained with acetolacmoid to evaluate chromatin configuration, while the cleaved ones were cultured in SOF + 0.4% BSA up to the blastocyst stage. Data were analyzed by ANOVA statistical analysis after arcsine transformation of the value percentages. Ultrasonographic monitoring showed a significant increase in the number of follicles (mean ± SEM) present in the ovaries from Day 8 to Day 11 of treatment in group A compared to group B (Day 8: 19 ± 5.1 vs. 13 ± 3.4, P > 0.05; Day 9: 20.1 ± 4.6 vs. 14.1 ± 2.4, P > 0.001; Day 10: 22.5 ± 6.1 vs. 14.7 ± 2.7, P > 0.001; Day 11: 25.3 ± 5.1 vs. 20.5 ± 4.1, P > 0.05), thus confirming that GnRH antagonist administration enhances ovarian response to exogenous FSH stimulation. On the other hand, oocytes collected from untreated sheep lead to a higher blastocyst output (P = 0.014), as illustrated in the table. These results indicated that although GnRH antagonist administration caused a significant increase in the ovarian response to the hormonal treatment, the final blastocyst output was significantly lower compared to that of the control group. This finding seems to suggest an impairment in the developmental competence of treated sheep oocytes. Table 1. In vitro maturation, fertilization, and developmental capacity of oocytes collected from follicles of GnRH antagonist-treated (group A) and untreated (group B) sheep This work was supported by funds from the Spanish MEC (projects SC 00-051-C3.1 and HI2002-0004) and the Italian MIUR (cofin).

240OVINE PREPUBERTAL OOCYTE SHOWS ALTERATE GENE EXPRESSION AND LOW DEVELOPMENTAL COMPETENCE

The aim of this work was to evaluate developmental competence and gene expression of prepubertal and adult ovine oocytes. GV prepubertal and adult oocytes were matured, fertilized and cultured in vitro until blastocyst stage;; the time (days) needed to reach this stage was recorded. Blastocysts developed on different days were cultured for hatching to evaluate their quality in relation to cleavage rate. Adult and prepubertal GV oocytes and blastocyst-stage embryos produced, respectively, at 6 and 7 days were compared for quantitative expression of poly(A) polymerase (polyA-P), glucose transporter I (Glut-I), desmocollin II (desmoII), plakofilin (plako) and heat shock protein 70.1 (HSP70) genes. Confirming previous results (Ledda et al., 1996 Zygote 4, 343–348), fertilized prepubertal ovine oocytes developed to blastocyst stage at lower rates than the adult ones (19.9 v. 51.3%, respectively, P&lt;0.001) and this stage was delayed 24h in prepubertal compared to adult embryos (P&lt;0.01), reflecting a lower quality (Fenwick et al., 2002 Hum. Reprod. 17, 407–412) of the former. In fact, 44.7, 25.0, 30.3 and 0% of adult blastocysts were obtained after 6, 7, 8 and 9 days, respectively, of postfertilization culture compared to 0, 48.4, 34.3 and 17.2% of prepubertal ones. Faster-developed blastocysts showed higher hatching rate in both prepubertal (54.8%, 7 days of culture) and adult (89.8%, 6 days). Hatching rate dropped to 18.2% when blastocysts were obtained at 8–9 days in prepubertal and to 54.5% and 32.5% at 7 and 8 days, respectively, in adult embryos. Analysis of gene expression showed that HSP70, plako and desmo genes were not expressed in GV oocytes, and Glut-I mRNA was lower in prepubertal GV oocytes than in the adult ones (P&lt;0.01). All genes were expressed in blastocysts;; we found that Glut-I was at lower levels (P&lt;0.01) in prepubertal-derived blastocysts whereas HSP70 was highly expressed (P&lt;0.05) in prepubertal blastocysts than in those derived from adult oocytes. In conclusion this work shows that prepubertal ovine oocytes have a lower developmental competence compared to the adult ones, correlated to an altered gene expression during the growth phase of the oocyte and early embryonic development. Supported by MIUR (cofin).

The activation of gamma aminobutyric acid(A) receptors in the paraventricular nucleus of the hypothalamus reduces non-contact penile erections in male rats

Male rats show 4-6 penile erection episodes when put in the presence of an inaccessible receptive female. These non-contact penile erections were reduced dose-dependently by muscimol, a gamma aminobutyric acid (GABA)(A) receptor agonist, when given into the paraventricular nucleus of the hypothalamus (0.1, 0.5, 1 and 2 microg). In contrast, baclofen, a GABA(B) receptor agonist (2 microg) was ineffective. Muscimol reduction of non-contact penile erections was not seen when male rats were pretreated with bicuculline methiodide (2 microg) given 5 min before muscimol into the paraventricular nucleus. Since muscimol injected into the paraventricular nucleus also prevents penile erection induced by drugs (e.g. apomorphine, oxytocin or N-methyl-D-aspartic acid), the present results show that an increased GABAergic activity in the paraventricular nucleus can impair the expression of penile erection induced not only by drugs but also by sexual physiological stimuli.

EP 91073 prevents EP 80661-induced penile erection: new evidence for the existence of specific EP peptide receptors mediating penile erection

The effect of EP 91073, EP 51389, EP 70555 and EP 51216, peptide analogues of the growth hormone releasing peptide hexarelin, on penile erection induced by EP 80661 or EP 60761 injected into the paraventricular nucleus of the hypothalamus, was studied in male rats. Of the above peptides only EP 91073 (0.2-1 microg) was found capable of reducing penile erection induced by EP 80661 or EP 60761, when given into the paraventricular nucleus. Despite its ability to prevent EP peptide-induced penile erection, EP 91073 (1 microg) was unable to prevent penile erection induced by the dopamine receptor agonist apomorphine (50 ng), oxytocin (30 ng) and N-methyl-D-aspartic acid (50 ng), when given into the paraventricular nucleus 10 min prior to the above substances. The EP 91073-induced prevention of penile erection occurred with a reduction in the increase in nitric oxide production that occurs in the paraventricular nucleus concomitant to penile erection induced by EP 80661 and EP 60761, as measured by intracerebral vertical microdialysis. The present results are in line with the hypothesis that EP 80661 and EP 60761 induce penile erection by activating specific receptors in the paraventricular nucleus, located possibly in oxytocinergic neurons mediating penile erection, and show that EP 91073 acts as an antagonist of these EP peptide receptors mediating penile erection.

Penile erection induced by EP 80661 and other hexarelin peptide analogues: involvement of paraventricular nitric oxide

The effect of GAB-D-Trp(2-Me)-D-Trp(2-Me)-LysNH(2) (EP 80661), GAB-D-Trp(2-Me)-D-Trp(2-Me)-D-Trp(2-Me)-LysNH(2) (EP 60761), GAB-D-Trp(2-Me)-LysNH(2) (EP 91071) and GAB-D-Trp(2-Me)-D-beta Nal-Phe-LysNH(2) (EP 50885), four hexarelin peptide analogues that induce penile erection when injected into the paraventricular nucleus of the hypothalamus of male rats, on the concentration of NO(2)(-) and NO(3)(-) in the paraventricular dialysate was studied in male rats. EP peptides (1 microg) induced penile erection and increased the concentration of NO(2)(-) and NO(3)(-) in the paraventricular dialysate. In contrast, hexarelin (1 microg) was ineffective on either penile erection or paraventricular NO(2)(-) and NO(3)(-). EP peptide-induced penile erection was prevented by the nitric oxide synthase inhibitor N(G)-nitro-l-arginine methylester given into the paraventricular nucleus (20 microg), which also reduced the concomitant increase of NO(2)(-) and NO(3)(-) concentration in the paraventricular dialysate. In contrast, the oxytocin receptor antagonist [d(CH(2))(5)Tyr(Me)(2)-Orn(8)]vasotocin (1 microg) given into the paraventricular nucleus, was ineffective on penile erection and on the NO(2)(-) and NO(3)(-) increase induced by EP peptides, despite its ability to prevent the sexual response induced by the above peptides when given into the lateral ventricles. The present results show that EP peptides induce penile erection by activating nitric oxide synthase in the paraventricular nucleus of the hypothalamus, possibly in the cell bodies of oxytocinergic neurons that control penile erection.

Differential orexigenic effects of hexarelin and its analogs in the rat hypothalamus: indication for multiple growth hormone secretagogue receptor subtypes

We have previously reported that hexarelin and some of its analogs, including EP 50885, stimulated GH secretion and feeding after systemic administration in the rat, whereas EP 40904 selectively stimulated food intake and EP 40737 only GH release. The precise mechanism of growth hormone-releasing peptides (GHRPs) actions is still unclear, but the integrity of the arcuate nucleus of the hypothalamus (ARC) appears crucial for their endocrine effects. To better characterize the site(s) and mechanisms(s) of the orexigenic action of GHRPs, we have investigated their effects after infusion into the arcuate, paraventricular, ventromedial and medial preoptic areas of the hypothalamus. Food intake was measured for 60 min following injection of the test compound (2 microg/rat). Hexarelin, EP 40904 and EP 50885 had significant orexigenic effects after injection into the ARC. A specific NPY antagonist significantly inhibited the effect of hexarelin, whereas a GHRH antagonist was ineffective. In the paraventricular nucleus, only EP 50885 stimulated feeding, whereas all peptides were ineffective in the ventromedial nucleus and medial preoptic area. Taken altogether, these results demonstrate that GHRPs are endowed with site-specific orexigenic actions and that endogenous NPY, but not GHRH, mediates these effects. The additional orexigenic action of EP 50885 in the paraventricular nucleus suggests the existence of a GHRP receptor subtype different from the already cloned one.

EP 60761- and EP 50885-induced penile erection: structure-activity studies and comparison with apomorphine, oxytocin and N-methyl-D-aspartic acid

The effect of 10 peptides structurally related to the growth hormone (GH) releasing peptide hexarelin, injected into the paraventricular nucleus of the hypothalamus (PVN), on penile erection was studied in male rats. Six out of the 10 peptides tested induced penile erection in a dose-dependent manner. Among them, the most potent were EP 80661, EP 60761 and EP 91072, which were active at doses of 20-200 ng. The potency of these peptides in inducing penile erection is comparable to that of apomorphine, oxytocin and N-methyl-D-aspartic acid similarly injected into the PVN. Other peptides found active were EP 50885, EP 90101 and EP 91071, which induced penile erection at doses of 200-2000 ng. In contrast, EP 51322, EP 70555, EP 51216 and EP 91073 were inactive, as were hexarelin, EP 40904 and EP 40737 in a previous study. The majority of EP peptides found active when injected into the PVN induced penile erection, although to a lesser extent, also when given systemically (endovenously). The proerectile effect of EP peptides was prevented by the oxytocin receptor antagonist [d(CH2)5 Tyr(Me)2-Orn8]-vasotocin given into the lateral ventricles but not into the PVN, by the nitric oxide (NO) synthase inhibitor N(G)-nitro-1-arginine methyl ester given either into the lateral ventricles or into the PVN, by the N-type Ca2+ channel blocker omega-conotoxin GVIA and by morphine, but not by the dopamine receptor antagonist cis-flupenthixol or by the N-methyl-D-aspartic acid receptor antagonist dizolcipine, given into the PVN. As the structure-activity relationship of EP peptides for proerectile activity is different from those of other biological actions of these compounds, ie for GH release and eating behaviour, the present results suggest that EP peptides induce penile erection by acting on specific hypothalamic receptor sites that activate paraventricular oxytocinergic neurons projecting to extrahypothalamic brain areas that mediate this sexual function by a mechanism similar to that of dopamine receptor agonists, oxytocin and N-methyl-D-aspartic acid.

EP 60761 and EP 50885, two hexarelin analogues, induce penile erection in rats

The effect of hexarelin and four related peptide analogues, EP 40904, EP 40737, EP 50885 and EP 60761, injected into the paraventricular nucleus of the hypothalamus of male rats in doses between 2 and 2000 ng on spontaneous penile erection was studied. Of these peptides, EP 60761 and EP 50885, but not hexarelin, EP 40904 or EP 40737, increased dose-dependently the number of spontaneous penile erections. EP 60761 was active already at the dose of 20 ng, which induced the sexual response in 70% of the treated rats. The maximal response was induced by 200 ng of the peptide. EP 50885 was less potent than EP 60761, with 1000 ng being the minimal effective dose and 2000 ng as the dose required to induce the maximal response. At the doses used, both peptides also increased slightly the number of spontaneous yawning episodes. EP 60761- and EP 50885-induced penile erection was prevented by the oxytocin receptor antagonist [d(CH(2))(5)Tyr(Me)(2)-Orn(8)]vasotocin (0.1-1 microg) given intracerebroventricularly (i.c.v.), but not into the paraventricular nucleus (0.1-1 microg), by the competitive nitric oxide (NO) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) given either into the paraventricular nucleus (10-20 microg) or i.c.v. (75-150 microg), by the N-type Ca(2+) channel blocker omega-conotoxin-GVIA (2-5 ng) or by the opiate morphine (1-10 microg), but not by the dopamine receptor antagonist (Z)-4-[3-[2-(trifluoromethyl)-9H-thioxanthen-9-ylidene]propyl]-1-p ipe razine-ethanol (cis-flupenthixol) (10 microg) or by the N-methyl-D-aspartic acid (NMDA) receptor antagonist (5R, 10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine ((+)-MK-801) (1 microg), all given into the paraventricular nucleus before either peptide. The present results show that EP 60761 and EP 50885 induced penile erection by increasing central oxytocin transmission, possibly by activating NO synthase in the cell bodies of oxytocinergic neurons located in the paraventricular nucleus that control penile erection.

Effect of excitatory amino acid, dopamine, and oxytocin receptor antagonists on noncontact penile erections and paraventricular nitric oxide production in male rats

In male rats, noncontact erections occur concomitantly with an increase in NO2- and NO3- in the paraventricular nucleus of the hypothalamus (PVN). In the present study, both responses were reduced by the blockade of PVN excitatory amino acid receptors by dizocilpine, (+)-MK-801(1 and 5 microg), but not by 6-cyano-7-nitro-quinoxaline-2,3-dione (5 microg) or (+)-2-amino-4-phosphono-butanoic acid (5 microg). Also ineffective when injected into the PVN were the dopamine antagonists SCH 23390 (5 microg), S(+)-raclopride (10 microg), and cis-flupenthixol (10 microg), and the oxytocin antagonist d(CH2)5Tyr(Me)2-Om8-vasotocin (1 microg). However, when the last was given into the lateral ventricles, it reduced noncontact erections without modifying NO2- and NO3- increases. These results suggest that excitatory amino acid transmission increases in the PVN during noncontact erections. This may contribute to increased NO production in the PVN, and it may activate oxytocin neurons mediating this sexual response.

Activation of gamma-aminobutyric acid(A) receptors in the paraventricular nucleus of the hypothalamus reduces apomorphine-, N-methyl-D-aspartic acid- and oxytocin-induced penile erection and yawning in male rats

The effect of muscimol and baclofen injected into the paraventricular nucleus of the hypothalamus on penile erection and yawning induced by apomorphine, oxytocin and N-methyl-D-aspartic acid (NMDA) was studied in male rats. Muscimol (20-200 ng), but not baclofen (200 ng), injected into the paraventricular nucleus of the hypothalamus 10 min before apomorphine (50 ng), oxytocin (10 ng) or NMDA (50 ng) reduced penile erection and yawning induced by the above compounds given into the paraventricular nucleus. Bicuculline (250 ng) injected into the paraventricular nucleus 5 min before muscimol (100 ng) prevented the inhibitory effect of muscimol on penile erection and yawning induced by apomorphine, oxytocin and NMDA. The present results show that gamma-aminobutyric acid (GABA) inhibits penile erection and yawning by acting on GABA(A) receptors in the paraventricular nucleus of the hypothalamus.

Morphine injected into the paraventricular nucleus of the hypothalamus prevents noncontact penile erections and impairs copulation: involvement of nitric oxide

Male rats show four to six penile erection episodes when put in the presence of an inaccessible receptive female for 80 min. These noncontact erections occur concomitantly with an increase in nitric oxide production in the paraventricular nucleus of the hypothalamus. This is shown by the increases in the NO2- and NO3- concentrations in the paraventricular dialysate obtained from these males by in vivo microdialysis. The NO2- concentration increased from 0.75 +/- 0. 10 microm to 2.89 +/- 0.39 microm and that of NO3- from 4.13 +/- 0. 58 microm to 9.5 +/- 1.2 microm. Morphine (0.5, 1 and 5 microg), given unilaterally into the paraventricular nucleus 15 min before the introduction of the receptive female, prevented the NO2- and NO3- increases, and noncontact erections, dose-dependently. In contrast, the kappa opioid receptor agonist U-69 593 (5 microg) was ineffective. The effects of morphine on NO2- and NO3-, and on noncontact erections, were prevented by the opiate receptor antagonist naloxone (10 microg) injected into the paraventricular nucleus 15 min before morphine. The NO2- and NO3- concentrations were also increased in the paraventricular dialysate of male rats during copulation, i.e. when in copula penile erections occurred. As found with noncontact erections, morphine, but not U-69 593, injected into the paraventricular nucleus prevented the NO2- and NO3- increases and impaired copulatory behaviour, and naloxone prevented these responses when given before morphine. Although some diffusion of the opiate to surrounding brain areas cannot be completely ruled out, the present results suggest that morphine acts through mu receptors in the paraventricular nucleus to impair noncontact erections and copulation. These effects of morphine are apparently mediated by a prevention of the increased nitric oxide production that occurs in the paraventricular nucleus of the hypothalamus of male rats during sexual activity.

The oxytocin antagonist d(CH2)5Tyr(Me)2-Orn8-vasotocin reduces non-contact penile erections in male rats

Male rats show four to six penile erection episodes when put for 80 min in the presence of an inaccessible receptive female. These non-contact penile erections were reduced dose-dependently by d(CH2)5Tyr(Me)2-Orn8-vasotocin, a potent and selective oxytocin receptor antagonist, when given into the lateral ventricles (0.1, 0.5 and 1 microg), but not when given into the paraventricular nucleus of the hypothalamus (0.1 and 1 microg). In contrast, non-contact erections were reduced by N(G)-nitro-L-arginine methyl ester, a competitive inhibitor of nitric oxide synthase, given into the lateral ventricles (50, 100 and 200 microg), or into the paraventricular nucleus (10 and 20 microg). The present results show that central oxytocin is involved in the expression of penile erection induced not only by drugs but also by sexual physiological stimuli.

Different effects of omega-conotoxin on penile erection, yawning and paraventricular nitric oxide in male rats

A dose of apomorphine or oxytocin that induces penile erection and yawning increases nitric oxide production in the paraventricular nucleus of the hypothalamus, as determined by the increase in NO2- and NO3- concentration induced by these substances in the paraventricular dialysate obtained from male rats. All the above responses were prevented by a dose of omega-conotoxin-GVIA as low as 5 ng. This potent inhibitor of N-type Ca2+ channels was injected into the paraventricular nucleus 15 min before apomorphine (50 ng) or oxytocin (10 ng). In contrast, omega-conotoxin was ineffective when the above responses were induced by N-methyl-D-aspartic acid (50 ng). The peptide toxin (5 ng) was also ineffective on the penile erection and yawning induced by the nitric oxide donors sodium nitroprusside (50 microg) or hydroxylamine (50 microg), injected into the paraventricular nucleus. The present results suggest that omega-conotoxin-sensitive Ca2+ channels are involved in the activation of nitric oxide synthase, penile erection and yawning induced by apomorphine and oxytocin, but not by N-methyl-D-aspartic acid, at the paraventricular level.

Nitric oxide production is increased in the paraventricular nucleus of the hypothalamus of male rats during non-contact penile erections and copulation

Male rats put in the presence of a receptive female rat that they can see, hear and smell, but cannot touch, show penile erection episodes. These non-contact erections occur concomitantly with an increase in nitric oxide production in the paraventricular nucleus of the hypothalamus, as detected by the increase in the NO2- and NO3- concentration in the paraventricular dialysate obtained from these males by in vivo microdialysis. NO2- concentration increased from 0.81+/-0.12 to 2.51+/-0.43 microM and that of NO3- from 4.50+/-0.73 to 8.31+/-2.3 microM. The NO2- increase was prevented by the nitric oxide synthase inhibitor NG-nitro-L-arginine methylester (20 microg) given unilaterally in the paraventricular nucleus, which also prevented non-contact erections. In contrast, the nitric oxide scavenger haemoglobin (20 microg) prevented the NO2- increase, but not non-contact erections; while the guanylate cyclase inhibitor methylene blue (20 microg) was ineffective on either response. NO2-and NO3- concentration was also increased in the paraventricular dialysate of male rats during in copula penile erections, that is, when sexual activity was allowed with the receptive females. As found with non-contact erections, NG-nitro-L-arginine methylester prevented NO2- increase and impaired copulatory behaviour; haemoglobin prevented NO2- increase only; and methylene blue was ineffective on either response. The present results confirm that nitric oxide is a physiological mediator of penile erection at the level of the paraventricular nucleus of the hypothalamus.

Prevention by morphine of N-methyl-D-aspartic acid-induced penile erection and yawning: involvement of nitric oxide

The effect of morphine on the increase of NO2- and NO3- concentration in the dialysate obtained with a microdialysis probe implanted in the paraventricular nucleus of the hypothalamus, and penile erection and yawning induced by N-methyl-D-aspartic acid (NMDA) was studied in male rats. NMDA (50 ng) injected in the paraventricular nucleus of the hypothalamus, induced penile erection and yawning and increased NO2- from 1.10 +/- 0.28 microM to 7.30 +/- 1.10 microM and NO3- from 5.05 +/- 0.71 microM to 11.03 +/- 1.61 microM. Morphine (1-10 microg), but not U-69,593 (10 microg), a selective agonist of the kappa opiate receptor subtype, prevented in a dose-dependent manner NMDA-induced increase in NO2- and NO3- concentration when injected in the paraventricular nucleus 15 min before NMDA. Morphine prevention of NMDA-induced NO2- and NO3- increase was related to a concomitant decrease in the number of penile erection and yawning episodes induced by the excitatory amino acid. Morphine effect was not observed in male rats treated with the opiate receptor antagonist naloxone (10 microg) microinjected in the paraventricular nucleus 15 min before morphine. The present results suggest that morphine prevents an NMDA-induced increase in paraventricular NO production, penile erection, and yawning by inhibiting NO synthase activity in the paraventricular nucleus of the hypothalamus through the stimulation of opioid receptors of the micro subtype.

N-methyl-D-aspartic acid-induced penile erection and yawning: role of hypothalamic paraventricular nitric oxide

A dose of N-methyl-D-aspartic acid (NMDA, 50 ng) that induces penile erection and yawning when injected into the paraventricular nucleus of the hypothalamus, increased the concentration of NO2- from 1.10 +/- 0.28 microM to 7.32 +/- 1.12 microM and of NO3 from 4.96 +/- 0.69 microM to 10.5 +/- 1.61 microM in the paraventricular dialysate obtained from male rats by in vivo microdialysis. NO2- concentration was not increased by (+/-)-alpha-(amino)-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA, 100 ng) or by trans-(+/-)-1-amino-1,3-cyclopentanedicarboxylic acid (ACPD) (100 ng), which were unable to induce these behavioral responses. N-Methyl-D-aspartic acid effect on NO2- concentration, penile erection and yawning was prevented by dizolcipine (MK-801) (10-100 ng) or by the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (20 microg), but not by the oxytocin receptor antagonist [d(CH2)5,Tyr(Me)2,Orn8]vasotocin (100 ng), or by the guanylate cyclase inhibitor methylene blue (20 microg) given in the paraventricular nucleus 15 min before N-methyl-D-aspartic acid or by the dopamine receptor antagonist haloperidol (0.5 mg/kg) given intraperitoneally 30 min before N-methyl-D-aspartic acid. In contrast, the nitric oxide scavenger hemoglobin (20 microg) given in the paraventricular nucleus prevented N-methyl-D-aspartic acid-induced NO2- concentration increase, but was unable to prevent penile erection and yawning. The results suggest that N-methyl-D-aspartic acid induces penile erection and yawning by increasing nitric oxide synthase activity in the paraventricular nucleus of the hypothalamus, possibly in the cell bodies of oxytocinergic neurons projecting to extra-hypothalamic brain areas and mediating these behavioral responses.

Prevention by morphine of apomorphine- and oxytocin-induced penile erection and yawning: involvement of nitric oxide

The possible involvement of nitric oxide in the prevention by morphine of apomorphine- and oxytocin-induced penile erection and yawning was investigated by measuring the concentration of NO2- and NO3- in the dialysate obtained with a vertical microdialysis probe implanted in the paraventricular nucleus of the hypothalamus of male rats. Either apomorphine (80 micrograms/kg s.c.) or oxytocin (30 ng i.c.v.) increased significantly basal NO2- and NO3- concentration in the paraventricular dialysate, penile erection and yawning. Morphine (1.5 and 10 mg/kg i.p.) prevented dose-dependently either apomorphine or oxytocin responses when given 15 min before apomorphine or oxytocin. Prevention by morphine of apomorphine and oxytocin responses was abolished by naloxone (3 mg/kg i.p.) given 15 min before morphine. Morphine prevented apomorphine and oxytocin responses also when given in the lateral ventricles or directly in the paraventricular nucleus. In contrast, the selective agonist of the kappa opioid receptor subtype U-69,593 was found to be ineffective. The present results confirm previous findings showing that morphine acts through mu receptors in the paraventricular nucleus to prevent apomorphine and oxytocin-induced penile erection and yawning and suggest that this morphine effect is mediated by a decreased activity of nitric oxide in the paraventricular nucleus of the hypothalamus.

Oxytocin increases nitric oxide production in the paraventricular nucleus of the hypothalamus of male rats: correlation with penile erection and yawning

A dose of oxytocin (50 ng i.c.v.) that induces penile erection and yawning, increased the concentration of NO2- from 0.98 +/- 0.29 to 4.2 +/- 0.79 microM and of NO3- from 5.6 +/- 0.33 to 12.03 +/- 0.99 microM in the dialysate from the paraventricular nucleus of the hypothalamus of male rats, as measured by in vivo microdialysis. NO2- concentration was also increased by [Thr4, Gly7]-oxytocin (100 ng i.c.v. and oxytocin(8) (1 microgram i.c.v.) which also induced penile erection and yawning, but not by oxytocin(1-6) (1 microgram i.c.v.) or oxytocin (7-9) 1 microgram i.c.v.), which were unable to induce these behavioral responses. The oxytocin effect on NO2 concentration, penile erection and yawning was prevented by the oxytocin receptor antagonist. d(CH2)5,Tyr(Me)-Orn8-vasotocin (1 microgram i.e.v.) or by the nitric oxide synthase inhibitor, NG-nitro-1-arginine methyl ester (200 micrograms i.c.v.), but not by the dopamine receptor antagonist, haloperidol (0.5 mg/kg i.p.). The nitric oxide scavenger, hemoglobin (200 micrograms i.c.v.), prevented oxytocin-induced NO2- concentration increase, but was unable to prevent penile erection and yawning. Methylene blue (300 micrograms i.c.v.) an inhibitor of guanylate cyclase, was ineffective on oxytocin-induced NO2- concentration increase, but prevented the behavioral responses. The results suggest that oxytocin induces penile erection and yawning by increasing nitric oxide synthase activity in the cell bodies of oxytocinergic neurons projecting to extra-hypothalamic brain areas and mediating the behavioral responses.

Dopamine agonists increase nitric oxide production in the paraventricular nucleus of the hypothalamus: correlation with penile erection and yawning

A low dose of apomorphine (80 micrograms/kg s.c.), a mixed D1/D2 agonist that induces penile erection and yawning, increased the concentration of NO2-from 1.12 +/- 0.45 microM to 3.8 +/- 0.75 microM and NO3-from 5.53 +/- 0.82 to 11.25 +/- 2.30 microM in the dialysate collected from the paraventricular nucleus of the hypothalamus of male rats by in vivo microdialysis. The NO2-concentration was also increased by LY 171555 (50 micrograms/kg s.c.), a D2 agonist that induces penile erection and yawning, but not by SKF 38393 (5 mg/kg s.c.), a D1 agonist with no effect on these responses. Conversely, apomorphine's effect on NO2-was prevented by haloperidol (0.5 mg/kg i.p.), a mixed D1/D2 antagonist and L-sulpiride (25 mg/kg i.p.), a D2 antagonist, but not by the D1 agonist SCH 23390 (50 micrograms/kg s.c.), although all three compounds prevented penile erection and yawning. The apomorphine effect on NO2-, penile erection and yawning was also prevented by the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (200 micrograms i.c.v.). The nitric oxide scavenger haemoglobin (200 micrograms i.c.v.) also prevented the NO2-increase, but was ineffective against penile erection and yawning. In contrast, the oxytocin antagonist d(CH2)5Tyr(Me)-Orn8-vasotocin (1 microgram i.c.v.) and the guanylate cyclase inhibitor methylene blue (300 micrograms i.c.v.) had no effect on the NO2-increase, but did prevent the behavioural responses. We infer from this that dopamine agonists induce penile erection and yawning by acting on D2 receptors that increase nitric oxide synthase activity in the cell bodies of paraventricular oxytocinergic neurons projecting to extra-hypothalamic brain areas.